Cook-stove thermometer



S. E L W 0 N K COOK STOVE THERMOMETER Patented July 31, 1894.

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Hdilgesses UNTTED STATES PATENT OFFICE.

ARBIE PORTER KNOWLS, OF ST. FRANCIS, ARKANSAS.

CO-OK-STOVE THERMOMETER.

SPECIFICATION fOI'mllg part 0f Letters Patent NO. 523,794,dai7ed July 31, 1894.

I Application tiled November 17, 1893. Serial No. 491.245- (NO 11101910 To all whom it may concern.-

B e it known that LARBIE PORTER KNOWLES, a citlzen of the United States, residing at St. Francis, in the county of Clay and State of- Arkansas, have invented a new and useful Thermometer for-Cook-Stoves, of 4which the following is a specification.

My invention relates to an oven thermometer for cook-stoves, and it has for its object to provide a simple, inexpensive, and elhcientV pparatus adapted to be applied to the oven oor.

.A further object of my invention is to prov1de a device of the class namedin which the connections between the co-operating parts are positive and do not depend upon gearing, springs, lWeights, and other analogous features whlch are affected by the position of the apparatus, or are liable to disarrangement 0r lnJury through excessive heat or after eX- tended use.

Further objects and advantages of this invention will appear in the following description and the novel features thereof will be particularly pointed out in the appended claims. l

In the drawings: Figure l is a perspective view of a pyrometer embodying my invention, applied 1n the operative position to an oven door. Fig. 2 is a view of the device with the rear plate of the casing removed to show the construction of the mechanism. Fig. 3 is a vertical section of the apparatus.

Similar numerals of reference indicate cor responding parts in all the figures of the drawings.

1 designates the casing of the pyrometer, which is provided with aremovable rear plate 2, slidably fitted thereto and perforated to allow free communication between the oven and the interior of the casing; and 3 represents the dial, which is located on the outside of the oven door, the latter being shown at 4. This dial is provided with graduations indicating degrees, and is preferably made segment-shaped as shown.

Within the casing, and parallel with and adjacent to one side thereof, is arranged anl expansible metallic tube 5, which is firmly secured at one end tothe casing by means of a rivet 6. The free end of this expansible tube is pivotally connected to the short arm of a liat lever 7, and to the long arm of said lever is pivotally connected one end of an expansible tube 8. The other end of the tube .8 is pivotally connected to the short arm of a lever 9, which is located opposite to the lever 7. 10 represents a pointer, which is carried by a spindle 11, mounted in the casing, and to the inner end of this spindle is fixeda crankarm 12, the free end of which is connected, by means of an expansible tube 13, to the eX- tremity of the long arm of the lever 9. It will be seen that the connections between the expansible tubes and the levers, and the connection between the tube 13 and the crankarm 12, are pivotal, whereby displacement of the parts during operation is prevented.

I preferably employ brass in the construction of the expansible tubes, as being particularly sensitive to the action of heat, and it will be observed that, by the relative arrangement of the parts, the longitudinal expansion of the tubes is magnified by means of the levers to cause a perceptible variation of the pointer for each degree more or less of heat.

It will be understood that -the use of tubes or tubular rods 5, 8 and 13, as the expansible -members of the structure, is advantageous for the reason that this construction of rod provides the necessary transverse strength, and at the same time presents the maximum surface with the minimum cross section of material for the action of the heat, thereby yrendering the device more sensitive to the ac tion of the heat. l By avoiding the use of connections whic depend'wholly or partly upon the relative positions of the parts,I am enabled to place the pyrometer in any desired position without affecting the operation thereof.

Having described my invention, what I kclaim is- 1. The combination with a casing, a dial, and a pointer traversingsaid dial, of a crankarm fixed to the spindle of thepointer, an expansible tube 5 permanently Iixed at one end to the casing, a lever 7 having its shorter arm pivotally connected to the free end of the tube 5, a similar lever 9, an expansible tube 13 connecting the extremity of the longer arm o f the lever 9 with the extremity of said crank- IOO arm, and an expansible tube S connecting the longer arm of the lever 7 with the shorter arm of the lever 9, the connection between the crank-arm and levers and the expansibie tubes 8 and 13' being pivotal, substantially as specified.

2. The combination 0E a casing, a dial, a pointer traversing said dial, and a series of expansible tubes and connecting levers arranged within the casing and operatively connected to the spindle of said pointer, the casing being provided with a removable perforated rear plate which is slidably fitted upon the edges of the casing, substantially as specied.

In testimony that I claim the foregoing as my own I have hereto aixed my signature in lche presence of two witnesses.

ARBIE PORTER KNOWLES.

Witnesses:

W. S. LIDDELL, CHARLES THoMANsoN. 

